The invention relates to an improved drive assembly for rotating and supporting a wheel to be serviced on a tire service machine. Furthermore, the invention relates to a tire changer for mounting and demounting a tire onto and from a rim, using an improved drive assembly. Additionally, the invention relates to a wheel balancer for balancing a wheel using an improved drive assembly.
A drive assembly for rotating and supporting a wheel in a tire mounting and demounting machine is known from EP patent application 1 724 125. A shaft being arranged vertically is directly coupled to an electro motor being arranged beneath the shaft. A rim to be serviced is placed on a wheel support driven by the shaft. When rotating, the shaft rotates a cone which clamps the rim of a wheel to be serviced against the wheel support. The whole driving force of the rotating movement for the drive assembly has to be applied by the motor which has to be powerful. Therefore, it is inevitable to have a big and powerful motor which is expensive and takes installation space. Furthermore, the arrangement of the known drive assembly provides another disadvantage. The mounting and demounting procedure that follows the clamping of a rim on the wheel support surface, is done by means of relatively high operation forces, which in general have to be accepted in a solid frame the drive assembly is accommodated.
A balancing machine for rotating bodies is known from EP patent application 1 367 374. A motor drives a shaft supporting a rotating body, in particular a wheel. The shaft is supported by tension members to measure the unbalance of the rotating body. The motor, which shall not produce noticeable vibrations in order to avoid a negative influence to the measuring results of the balancing machine, drives the rotating body. Therefore, normally the motor is chosen bigger than required to prevent the motor from producing noticeable vibrations. This provision of a motor being bigger than required also rises the costs for a balancing machine for rotating bodies.
Therefore, it is an object of the present invention to provide a drive assembly for tire service machines that requires a motor providing less torque and having smaller dimensions than that of tire service machines of the prior art.